Wi-Fi's promise for cell carriers running out of options

Although vendor-written, this contributed piece does not advocate a position that is particular to the author's employer and has been edited and approved by Network World editors.

Growing cellular data bandwidth demands driven by the runaway growth of smart devices and bandwidth-hungry applications is forcing many mobile carriers to look for alternate data solutions to relieve their strained networks. With Wi-Fi available on most mobile devices, Wi-Fi offload is being embraced by a number of carriers around the world as a practical part-time solution because it is cost-effective, relatively easy to adopt and free of licences/regulatory requirements.

To make Wi-Fi offload work, carriers are either reaching agreements with local/global hotspot aggregators, installing independent hotspot infrastructure, or doing both, just to facilitate Internet access for the hotspot-connected subscriber. Once the subscriber is connected thru a Wi-Fi hotspot, the data load on the carrier's cellular network is relieved, leaving more bandwidth to be shared by other customers.

While carriers are unable to monetize data offload Wi-Fi hotspots and hotspot-connected subscribers miss out on regular carrier services, it would be hard for cellular tech to single-handedly keep pace with the predictions of explosive bandwidth demands. Moreover, such upgrades would be costly, time-consuming and often face radio spectrum constraints.

That's why industry experts are advocating carriers to make Wi-Fi an important and integrated part of their overall network infrastructure, even beyond offload. Integrating sophisticated Wi-Fi solutions into their core networks would open up a number of opportunities for carriers, making it possible to attract more customers and provide better service to existing ones, thereby strengthening their position versus competitors and even bring in more revenues.

Opportunities other than the inherent benefit of data offload includes:

* Consistent carrier-grade experience over Wi-Fi: Customer experience can be made consistent and carrier-grade at carrier-backed Wi-Fi hotspots, once sophisticated and integrated hotspot solutions are deployed as part of a carefully planned Wi-Fi strategy. Tight integration means simplified, seamless handovers to Wi-Fi from cellular and vice-versa. Similarly, advanced Wi-Fi security can be provisioned using unified EAP-SIM/EAP-AKA procedures. Also, the integration would allow customers to seamlessly access regular carrier services, including voice, messaging and other value-added services. Even billing could be integrated. [Also see: "Is patching cellular gaps with Wi-Fi secure?"]

* Easy injection of broadband capacity and coverage: Using strategically located public Wi-Fi hotspots that provide carrier-grade Wi-Fi access, enough capacity could be easily injected into dense metropolitan areas that are currently reeling under a capacity crunch. What's more, the same technology could be used to extend coverage where cell coverage is weak or nonexistent.

* Carrier-managed Wi-Fi services for businesses/organizations: Providing managed Wi-Fi services to businesses could be a new business model for carriers that are seriously considering Wi-Fi. The services would be ideal for SMBs, such as small-scale retail outlets, hospitality enterprises or branch offices, all of which are becoming increasingly reliant on Wi-Fi for efficiency, but lack the budget to install and maintain quality Wi-Fi services.

* Carrier-hosted Wi-Fi services at venues: A slightly different business model would involve providing hosted and managed Wi-Fi services for venues such as stadiums, parks, convention centers, auditoriums, exhibit halls and arenas. Since most of participants use event Wi-Fi services for live blogging, coverage, personal use, etc., carrier-hosted Wi-Fi services can represent additional sources of revenues and branding opportunities.

* Multiplexing carrier Wi-Fi hotspot services over carrier hosted/managed Wi-Fi services: As the part of carefully thought Wi-Fi strategy, sophisticated Wi-Fi solutions when deployed for hosted/managed Wi-Fi services can enable carriers to multiplex carrier hotspot services over hosted/managed ones. Such a multiplexing will allow carrier to expand their public Wi-Fi footprint and allow their subscribers to access hotspot services, when in the range of carrier hosted/managed Wi-Fi services.

* Reselling excess Wi-Fi capacity: Deployment of sophisticated Wi-Fi infrastructure will also allow carriers to neatly resell excess Wi-Fi capacity to third parties, such as other carriers, hotspot aggregators or MVNOs. This would ensure that available Wi-Fi capacity is utilized at its best and further justify the Wi-Fi investment.

* Scope to launch new plans/services: With an integrated small cell carrier Wi-Fi network in place, carriers can have complete visibility and control over the subscriber's Wi-Fi activity, enabling them, for example, to offer usage and/or quality-of-service based plans. Carriers could also rollout exclusive Wi-Fi access plans to customer beyond their cellular subscribers.

* Complement to future HetNets strategies: HetNets strategies rely on using a mixture of cells of different sizes, air interfaces and spectrum bands, to efficiently and effectively address coverage holes and the every growing capacity crunch. A carrier-grade Wi-Fi network, on account of its cost-effectiveness, ubiquity of Wi-Fi support in most mobile devices and low drain on battery power, can easily complement and become part of a carrier's HetNets strategy.

Many large cellular carriers are waking up to the opportunities of an integrated Wi-Fi approach and are evaluating their options. However, there are many challenges that need to be addressed to maximize the gains, including:

* Site acquisition: Strategic locations in public places, private buildings or on utility infrastructure (such as power/streetlight poles) needs to be identified and acquired, either through approvals or lease agreements.

* Backhaul: Effectively backhauling the Wi-Fi traffic from carrier-backed access points is another major challenge. Various locations can have different backhaul constraints. Moreover, depending on which route you go, you may need another box that requires an additional power outlet, mounting place. Ideally, the carrier-grade Wi-Fi AP should provide a host of integrated backhaul options, one or more of which are suitable for most locations. [Also see: "Wireless backhaul to go next-generation by 2012: IDC"]

* Scalability: Since Wi-Fi hotspots signal levels are limited, a metro Wi-Fi network infrastructure may grow to hundreds of thousands of Wi-Fi nodes. Therefore, scalability is another key challenge in the integrated Wi-Fi approach, and the solution considered must be mature enough to handle it gracefully and flexibly, without requiring too much administration and without any performance degradation.

* Carrier-grade OAM: Support of carrier-grade OAM is necessary for building a carrier class Wi-Fi infrastructure. The OAM function should ensure that Wi-Fi nodes can be automatically discovered and appropriately provisioned at their respective locations, once booted up. In case of a software failure, the node should be able to do recovery itself in most cases, but where manual support becomes mandatory, it should be easy to access and test the Wi-Fi node. What's more, software upgrades should be seamless. Further, the OAM must ensure that the health of the carrier Wi-Fi network is continuously monitored and reported in real time for all failures points and all relevant performance metrics, in order to address inefficiencies as quickly as possible. Similarly, other requirements of a carrier-grade OAM, including the integration with carrier's centralized NMS, collection of network statistics, etc., should be implemented.

* Carrier-grade performance: Solutions should use a carrier-grade platform/OS, limit unnecessary unicast/broadcast/multicast traffic, operate on capacity-optimized radio channels all the time, etc.

* Business intelligence: Business intelligence should be built in, providing valuable stats such as time of day and location of the user and device and traffic metrics, all of which can help a carrier appropriately plan for future Wi-Fi expansion.

* Virtualized architecture: Having an exclusive virtualized architecture is key to maximizing the benefits of a carrier-deployed Wi-Fi network, because it supports multiple SSIDs (on a single radio) that can be configured independently for different VLANs, security, AAA, DHCP, mobility and other important parameters. That makes it possible for a single Wi-Fi node to support multiple Wi-Fi networks over a limited number of radios, enabling carriers to multiplex various service levels and share/resale capacity with third parties.

* Architectural flexibilities: This refers to a host of hardware and software issues that should be present in a carrier-grade Wi-Fi solution to accommodate various deployment scenarios. Hardware flexibility means working with a variety of hardware enclosures, power options, mounting options, etc. Software flexibility refers to all those customization functions needed for various deployment constraints, such as the availability of a number of tunneling options (GRE, L2VPN, PMIP, L2TP, etc.) to tunnel Wi-Fi traffic to a particular core network. Another example may be support of a number of discovery mechanisms, such as L2, L3 using DNS, L3 using DHCP option 43, etc.

* Seamless mobility and roaming support: Mobility and roaming across Wi-Fi nodes and between Wi-Fi and cellular are other major challenges. The solution must support technologies such as L2VPN, L2TP, PMIP and CAPWAP to handle Layer 2/Layer 2 mobility event(s), and should support or easily upgradable to upcoming Hotspot 2.0 and 802.11u to effectively automate network discovery, registration and provisioning steps required for seamless inter-carrier Wi-Fi roaming, or between inter-/intra-carrier roaming between cellular and Wi-Fi nodes. [Also see: "802.11u and Hotspot 2.0 promise Wi-Fi users a cellular-like experience"]

* Robustness and compactness: Nodes deployed for a carrier-grade Wi-Fi network must be robust enough to bear harsh environment conditions (extreme temperatures, heavy rains, etc.) and should be robustly designed (with provisions like heat sinks) to deliver 24/7 service availability even at peak loads in dense metropolitan areas. At the same time, Wi-Fi nodes should be compact and aesthetically pleasing.

* Low cost of ownership: Ownership costs includes the one-time procurement and installation cost and the routine operational and maintenance cost afterward. With carrier-class Wi-Fi, one-time costs may be on the higher side compared to conventional Wi-Fi solutions, but certainly the carrier Wi-Fi solution must be architectured to reduce routine administration, maintenance and operation costs, thereby lowering the total cost of ownership for carrier grade Wi-Fi strategy.

The challenges make it evident that adoption of a carrier-grade and integrated Wi-Fi strategy is complex, requiring careful planning and an appropriately designed carrier-grade Wi-Fi solution, but once executed, the strategy can be leveraged multiple ways. Ultimately the distinction between the cellular and the Wi-Fi networks will disappear from customers' perspective and they will simply enjoy a reliable brand experience irrespective of the radio access technology used.

Gupta is presently working with BelAir Networks, a leader in multimode small cell wireless systems for mobile and fixed carriers. He has been in the field of Wi-Fi access and security for more than seven years and is a frequent contributor to leading magazines and blogs on wireless topics.

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